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Rotation period (astronomy)

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(Redirected fromRotation period)
Time that it takes to complete one rotation relative to the background stars
"Rotation period" redirects here. For the general concept, seeRotation period (physics).
Earth's rotation imaged byDeep Space Climate Observatory, with axis tilt

Inastronomy, therotation period orspin period[1] of acelestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to thesidereal rotation period (orsidereal day), i.e., the time that the object takes to complete afull rotation around itsaxis relative to the background stars (inertial space). The other type of commonly used "rotation period" is the object'ssynodic rotation period (orsolar day), which may differ, by a fraction of a rotation or more than one rotation, to accommodate the portion of the object'sorbital period around a star or another body during one day.

Measuring rotation

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For solid objects, such as rockyplanets andasteroids, the rotation period is a single value. For gaseous or fluid bodies, such asstars andgiant planets, the period of rotation varies from the object's equator to itspole due to a phenomenon calleddifferential rotation. Typically, the stated rotation period for a giant planet (such as Jupiter, Saturn, Uranus, Neptune) is its internal rotation period, as determined from the rotation of the planet'smagnetic field. For objects that are notsphericallysymmetrical, the rotation period is, in general, not fixed, even in the absence ofgravitational ortidal forces. This is because, although the rotation axis is fixed in space (by theconservation of angular momentum), it is not necessarily fixed in the body of the object itself.[citation needed] As a result of this, themoment of inertia of the object around the rotation axis can vary, and hence the rate of rotation can vary (because the product of the moment of inertia and the rate of rotation is equal to the angular momentum, which is fixed). For example,Hyperion, a moon ofSaturn, exhibits this behaviour, and its rotation period is described aschaotic.

Rotation period of selected objects

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Animation of theplanets and dwarf planets (Pluto andCeres) relative rotation period (usingsidereal time)
Celestial objectsRotation period with respect to distant stars, the sidereal rotation period (compared toEarth's mean Solar days)Synodic rotation period (mean Solar day)Apparent rotational period
viewed from Earth
Sun[i]25.379995 days (Carrington rotation)
35 days (high latitude)		25d 9h 7m 11.6s
35d		~28 days (equatorial)[2]
Mercury58.6462 days[3]58d 15h 30m 30s176 days[4]
Venus−243.0226 days[ii][5]−243d 0h 33m−116.75 days[6]
Earth0.99726968 days[3][iii]0d 23h 56m 4.0910s1.00 days (24h 00m 00s)
Moon27.321661 days[7] (equal tosidereal orbital period due tospin-orbit locking, asidereal lunar month)27d 7h 43m 11.5s29.530588 days[7] (equal tosynodic orbital period, due to spin-orbit locking, asynodic lunar month)none (due to spin-orbit locking)
Mars1.02595675 days[3]1d 0h 37m 22.663s1.02749125[8] days
Ceres0.37809 days[9]0d 9h 4m 27.0s0.37818 days
Jupiter0.41354 days(average)
0.4135344 days (deep interior[iv])
0.41007 days (equatorial)
0.4136994 days (high latitude)		0d 9h 55m 30s[3]
0d 9h 55m 29.37s[3]
0d 9h 50m 30s[3]
0d 9h 55m 43.63s[3]		0.41358 d (9 h 55 m 33 s)[10] (average)
Saturn0.44002+0.00130
−0.00091 days (average, deep interior[v])
0.44401 days (deep interior[iv])
0.4264 days (equatorial)
0.44335 days (high latitude)		10h 33m 38s+ 1m 52s
− 1m 19s[11][12]
0d 10h 39m 22.4s[13]
0d 10h 13m 59s[14]
0d 10h 38m 25.4s[14]		0.43930 d (10 h 32 m 36 s)[10]
Uranus−0.71833 days[3][ii]−0d 17h 14m 24s−0.71832 d (−17 h 14 m 23 s)[10]
Neptune0.67125 days[3]0d 16h 6m 36s0.67125 d (16 h 6 m 36 s)[10]
Pluto−6.38718 days[3][ii] (synchronous withCharon)–6d 9h 17m 32s−6.38680 d (–6d 9h 17m 0s)[10]
Haumea0.1631458 ±0.0000042 days[15]0d 3h 56m 43.80 ±0.36s0.1631461 ±0.0000042 days
Makemake0.9511083 ±0.0000042 days[16]22h 49m 35.76 ±0.36s0.9511164 ±0.0000042 days
Eris~15.786 days[17]~15d 18h 53m~15.7872 days

See also

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Notes

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  1. ^SeeSolar rotation for more detail.
  2. ^abcThis rotation is negative because the pole which points north of theinvariable plane rotates in the opposite direction to most other planets.
  3. ^Reference adds about 1 ms to Earth's stellar day given in mean solar time to account for the length of Earth's mean solar day in excess of 86400 SI seconds.
  4. ^abRotation period of the deep interior is that of the planet's magnetic field.
  5. ^Found through examination of Saturn'sC Ring

References

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  1. ^"Period".COSMOS - The SAO Encyclopedia of Astronomy. Retrieved2023-08-03.
  2. ^Phillips, Kenneth J. H. (1995).Guide to the Sun.Cambridge University Press. pp. 78–79.ISBN 978-0-521-39788-9.
  3. ^abcdefghijAllen, Clabon Walter & Cox, Arthur N. (2000).Allen's Astrophysical Quantities.Springer. p. 296.ISBN 0-387-98746-0.
  4. ^"ESO".ESO. Retrieved2021-06-03.
  5. ^Margot, Jean-Luc; Campbell, Donald B.; Giorgini, Jon D.; et al. (29 April 2021). "Spin state and moment of inertia of Venus".Nature Astronomy.5 (7):676–683.arXiv:2103.01504.Bibcode:2021NatAs...5..676M.doi:10.1038/s41550-021-01339-7.S2CID 232092194.
  6. ^"How long is a day on Venus?".TE AWAMUTU SPACE CENTRE. Retrieved2021-06-03.
  7. ^abAllen, Clabon Walter & Cox, Arthur N. (2000).Allen's Astrophysical Quantities.Springer. p. 308.ISBN 0-387-98746-0.
  8. ^Allison, Michael; Schmunk, Robert."Mars24 Sunclock — Time on Mars".NASA GISS.
  9. ^Chamberlain, Matthew A.; Sykes, Mark V.; Esquerdo, Gilbert A. (2007). "Ceres lightcurve analysis – Period determination".Icarus.188 (2):451–456.Bibcode:2007Icar..188..451C.doi:10.1016/j.icarus.2006.11.025.
  10. ^abcdeSeligman, Courtney."Rotation Period and Day Length". RetrievedJune 12, 2021.
  11. ^McCartney, Gretchen; Wendel, JoAnna (18 January 2019)."Scientists Finally Know What Time It Is on Saturn".NASA. Retrieved18 January 2019.
  12. ^Mankovich, Christopher; et al. (17 January 2019)."Cassini Ring Seismology as a Probe of Saturn's Interior. I. Rigid Rotation".The Astrophysical Journal.871 (1): 1.arXiv:1805.10286.Bibcode:2019ApJ...871....1M.doi:10.3847/1538-4357/aaf798.S2CID 67840660.
  13. ^Kaiser, M. L.; et al. (1980)."Voyager Detection of Nonthermal Radio Emission from Saturn".Science.209 (4462):1238–1240.Bibcode:1980Sci...209.1238K.doi:10.1126/science.209.4462.1238.hdl:2060/19800013712.PMID 17811197.S2CID 44313317.
  14. ^abAbel, Paul (2013). "Saturn".Visual Lunar and Planetary Astronomy. The Patrick Moore Practical Astronomy Series. New York, NY: Springer. pp. 149–171.doi:10.1007/978-1-4614-7019-9_8.ISBN 978-1-4614-7018-2.
  15. ^Lacerda, Pedro; Jewitt, David & Peixinho, Nuno (2008-04-02)."High-Precision Photometry of Extreme KBO 2003 EL61".The Astronomical Journal.135 (5): 1,749–1,756.arXiv:0801.4124.Bibcode:2008AJ....135.1749L.doi:10.1088/0004-6256/135/5/1749.S2CID 115712870. Retrieved2008-09-22.
  16. ^T. A. Hromakina; I. N. Belskaya; Yu. N. Krugly; V. G. Shevchenko; J. L. Ortiz; P. Santos-Sanz; R. Duffard; N. Morales; A. Thirouin; R. Ya. Inasaridze; V. R. Ayvazian; V. T. Zhuzhunadze; D. Perna; V. V. Rumyantsev; I. V. Reva; A. V. Serebryanskiy; A. V. Sergeyev; I. E. Molotov; V. A. Voropaev; S. F. Velichko (2019-04-09). "Long-term photometric monitoring of the dwarf planet (136472) Makemake".Astronomy & Astrophysics.625: A46.arXiv:1904.03679.Bibcode:2019A&A...625A..46H.doi:10.1051/0004-6361/201935274.S2CID 102350991.
  17. ^Szakáts, R.; Kiss, Cs.; Ortiz, J. L.; Morales, N.; Pál, A.; Müller, T. G.; et al. (2023). "Tidally locked rotation of the dwarf planet (136199) Eris discovered from long-term ground based and space photometry".Astronomy & Astrophysics.L3: 669.arXiv:2211.07987.Bibcode:2023A&A...669L...3S.doi:10.1051/0004-6361/202245234.S2CID 253522934.

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